Asymmetric Substitution by Alkynyl Copper Driven Dearomatization and Rearomatization

Abstract

Catalytic asymmetric transformations via dearomatization have developed into a widely applicable synthetic strategy, but heavily relied on the use of arenes bearing a heteroatom as the substrates. In this case, the challenging dearomatization is facilitated by the involvement of p‐orbital electron of the heteroatom. Different from the conventional substrate‐dependent model, here we demonstrate that the activation by d‐orbital electron of the transition metal center can perform as an intriguing type of driving force for dearomatization, which is applied to the development of a novel model for seldomly studied asymmetric alkynyl copper facilitated remote substitution reaction. A newly modified PyBox chiral ligand enables the construction of valuable diarylmethyl and triarylmethyl skeletons in high enantioselectivities. An unexpected tandem process involving sequential remote substitution/cyclization/1,5‐H shift leads to the formation of the enantioenriched C–N axis. Gram‐scale test and various downstream transformations highlight the robustness of this method and the potential chemical transformation space of the products. Preliminary mechanistic studies reveal a mononuclear Cu‐catalyzed remote substitution process.